1. Field of the Invention
The present invention relates to a treatment of arthritis, and in particular relates to a method for treating osteoarthritis by parathyroid hormone.
2. Description of the Related Art
Arthritis is a group of conditions involving damage to the joints of the body. Arthritis is the leading cause of disability in people older than fifty-five years old. The most common form of arthritis, osteoarthritis is a result of trauma to the joint, infection of the joint, or age.
OA is a clinical syndrome in which low-grade inflammation results in pain in the joints, caused by abnormal wearing of the cartilage that covers and acts as a cushion inside joints and destruction or decrease of synovial fluid that lubricates those joints. As the bone surfaces become less well protected by cartilage, the patient experiences pain upon bearing weight, including walking and standing. Due to decreased movement because of the pain, regional muscles may atrophy, and ligaments may become more lax.
It has been reported that phenotypic changes for OA chondrocytes are similar to those in epiphyseal growth plates, wherein chondrocytes undergo terminal differentiation, hypertrophy, mineral deposition and eventually apoptosis (Arthritis Rheum 1998; 41(2):284-9; Ann Rheum Dis 2000; 59(12):959-65; Osteoarthritis Cartilage 2000; 8(4):294-302). The OA chondrocytes express the marker proteins of hypertrophic chondrocytes, annexins, alkaline phosphatase and collagen type X (Col X), but eliminate the expression of collagen type II (Col II).
OA affects nearly 21 million people in the United States, accounting for 25% of visits to primary care physicians, and half of all NSAID (Non-Steroidal Anti-Inflammatory Drugs) prescriptions. It is estimated that 80% of the population will have radiographic evidence of OA by age 65, although only 60% of those will be symptomatic.
Thus, to treat arthritis, particularly osteoarthritis, methods and compositions for suppressing and inhibiting terminal differentiation, hypertrophy, mineral deposition and apoptosis are necessarily required.